After an earlier study defining immunolabeled lymphoid follicles, obstructed lymphatics, and granulomas of the diseased ilea of 24 Crohn's disease patients, we chose to trace the lymphatics of these cases and 10 additional by serial sectioning. Particular attention was given to establishing physical continuity between granuloma-obstructed lymphatics and lymphatics with 'lymphocytic thrombi'. Formalin-fixed paraffin-embedded tissue blocks from resected diseased ilea and proximal colons from 34 patients were reviewed. Patients were 13 men and 21 women, aged 14-60 years. Duration of disease ranged from 1 month to 10 years. Immunohistochemistry employed D2-40 antibody to label lymphatics and anti-CD68 to label granulomas. Twenty-nine of the 34 (85%) resection tissues had lymphangectasia, in mucosa, submucosa, and subserosa. In 53% of the specimens, lymphatics of the various layers were obstructed by granulomas that filled the lumina. In 44%, 15/34, there were also distended lymphatics that were totally plugged with lymphocytes. In 10 of the 15, serial sections revealed continuity between the lymphocyte-plugged lymphatics and the endolymphatic granulomatous obstruction downstream. In 5 of the cases, D2-40 immunostaining revealed redundant lymphatic endothelium interwoven with the granuloma cells. Granulomas totally obstruct lymphatics in all layers of the intestine in Crohn's disease. Upstream of these obstructions, lymphatics are distended with lymphocytes. The degree and extent of this potentially irreversible 'lymphangitis nodosa' have undoubtedly confounded treatment regimens and clinical trials. There currently are no imaging methods to demonstrate the lymphangitis, nor treatments to resolve it.

Chlamydia cause enteritis in young pigs and calves, and granulomas within intestinal lymphatics. Recently we called attention to the lymphangitis and lymphatic obstruction that occurs in Crohn's disease. We searched resected tissues from patients for evidence of chlamydia and sera for evidence of previous exposure to chlamydia. Immunohistochemistry and real-time PCR were employed to seek chlamydia in preserved tissues. In the IHC, antibody to C. trachomatis served as primary antibody; in the PCR, primers specific for Chlamydiaceae were employed. Commercial ELISA kits measured anti-chlamydia IgG and IgA against C. trachomatis antigen in sera derived from a population of patients different from that which yielded the tissue specimens. IHC revealed focal positive staining for chlamydia in tissues of 5 of 19 patients. Positive reacting cells occurred within dense inflammation, in sparsely scattered macrophages in the submucosa and subserosa. Tissues from 3 of 22 control subjects were positive. Real-time PCR done on ileal, colonic, and regional lymph node tissues revealed evidence of chlamydia in 3 of 33 patients. Serology for anti-chlamydia IgG revealed 2 positive values in 24 patients, while serology for anti-chlamydia IgA revealed 4 positives among the 24 patients, and 1 positive in the 15 controls. One patient and one control had both elevated IgG and IgA titers. The 4 patients with elevated IgA titers were from a single family of 6 with Crohn's disease, which had been previously described. Additional consideration needs to be given to the chlamydia species, including those of animal origin, which leave behind little evidence of their previous involvement.